The amount of data doesn't affect the speed at which a smaller amount of data goes through it. It's pretty close to the same. It does depend on the processor arch and there is a tiny translation penalty for 32 bit apps.

But, any 64-bit data can now fit in a register. Unmentioned, but 64-bit processors also tend to have more registers as well.

there are kernel hacks floating around, which enable PAE support in xp/vista/7 x86, but as others said, PAE has been disabled for a reason in the consumer editions of windows.
although the hacks do work, it's not advisable to use them, if you want to use the pc for multimedia/gaming stuff, because it's very likely you will run into incompatible drivers.

It's almost like all his knowledge of computer and OS stopped at 2005. Welcome to 2013. Why are you hell bend on keeping Windows XP? What's SO good about XP that keeps you from upgrading to Win7 x64?

high standards and unwillingness to compromise... if i have to drop the standards might as well move to win8 x64. and yes im already triple booting these 3OSes so there is no question of being stuck in 2005.

It's almost like all his knowledge of computer and OS stopped at 2005. Welcome to 2013. Why are you hell bend on keeping Windows XP? What's SO good about XP that keeps you from upgrading to Win7 x64?

He's one of the reasons why after 12 years, XP still has ~40% market share. The scary thing is that there are many, many systems admins that think like this, and mistake their own stubbornness, and unwillingness to adapt, as maintaining high standards.